1. Field of the Invention
The present invention generally relates to a decorative article. More specifically, the present invention relates to a decorative article and a timepiece.
2. Background Information
A superior aesthetic appearance is required for decorative articles such as exterior components for timepieces. Conventionally Pt, Ag, and other such metal materials have commonly been used as constituent materials for decorative articles to achieve such an objective. However, the hardness of these metal materials is usually relatively low, and decorative articles (particularly, exterior components and accessories for timepieces) configured from the aforementioned materials have had problems in that the surface is easily scratched and the aesthetic appearance is significantly degraded by long-term use.
In order to resolve such problems, a technique of nitriding the surface of a substrate composed, for example, of stainless steel or Ti with nitrogen has been used as a technique for hardening a substrate. An example is shown in Japanese Laid-Open Patent Application No. 11-318520, which is hereby incorporated herein by reference. However, nitriding treatment causes surface roughness, which changes the polished design. Mirror finished articles in particular are roughened and become clouded, and then cannot be used as decorative articles.
In view of this, a method of polishing the article to a mirror finish by mechanical polishing has been employed as a subsequent process. However, this method has had drawbacks in that hardness is reduced due to excessive scraping off of the hardened layer by polishing, and a layer with a subsequently unpolishable shape (a shape for which buffing is ineffective) cannot be treated.
In addition, a substrate that has been subjected to a nitriding treatment as described above has a low-quality color tone. Thus, it becomes difficult to apply the nitriding treatment to decorative articles wherein a superior design is required (particularly white and silver articles).
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved decorative article and timepiece. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.